Flyingboy,
Going a pb in practice is awfully difficult. But if they can do it, I don’t think it would hurt to do every once in a while. It would be a good confidence booster if nothing else. It seems like traditional distance training swimmers need rest to go a pb but I wouldn’t say it’s impossible. Chad le Clos used to do 10,000 meter practices in between prelims and finals at the world cup meets. He would still throw down some nasty times not that far off from his pb and get better week to week leading up to world champs. Perhaps he should have raced more leading up to the Olympics. Idk it’s hard to say if it would have made a difference.
I have tried to go pb’s in practice in 100’s. Even if I do a proper warm up and then do the 100 first thing, I still have no chance of going a pb. I have trouble hitting the first 50 speed without any rest. If I really push it to get out as fast as I need to, it doesn’t end well.
One thing I like to do for fun every once in a while is a 75 from a push trying to hit the pace of the last 75 race speed of a 100. I can hit this in practice. Since it’s an odd ball distance and only swum in practice, there is always a chance to go a pb.
Maybe you could try 75’s for 100’s and 150’s for 200’s and see what you get.